The present disclosure relates to articles which are functionalized and suitable for use in medical applications. These articles provide surfaces with improved performance.
Polycarbonates are synthetic thermoplastic resins derived from bisphenols and phosgene, or their derivatives. They can be formed from dihydroxy compounds and carbonate diesters, or by ester interchange. Polymerization may be in melt, interfacial, or in nonaqueous solution.
In some circumstances, it may be desirable to modify polymeric surfaces with sulfur containing compounds. This process is usually known as sulfonation. For example, sulfonating a polymeric surface will form a barrier layer with decreased permeability. In addition, sulfonation can be used to make transparent articles that have improved properties.
Sulfonation of a polymeric surface can be achieved in many ways. In some applications, it is necessary to neutralize the sulfonic acid groups generated by the sulfonation process. If unneutralized, the sulfonic acid groups can cause undesired degradation in the end use. For example, transparent sulfonated articles may turn hazy over time when exposed to high temperatures and high relative humidity. Neutralization may be achieved by contacting the sulfonated substrate with a solution containing a base, usually an aqueous solution.
With regard to the base, some polymers, such as vinyl polymers like polyethylene or polystyrene, are not sensitive to degradation caused by the base. Thus, strong bases, such as sodium hydroxide or ammonia, may be used to neutralize those polymers. However, condensation polymers such as polycarbonates, polyester carbonates, and polyesters are sensitive to degradation, especially with strong aqueous bases.
Polymers are used in medical applications where they come into contact with biological fluids such as blood, lymph, and plasma. It is desirable to provide polymers that have improved performance in such environments and applications.